Forgetting is also Important

It is not correct to think that God did anyinjustice by instilling in us a trait of forgetting past memories(--or--'in us the trait of forgetfulness').

No. He has intelligently designed our brain and with its amazing capabilities. If we keep on storing old details in memory, at a some point of in time there can be no room for thinking about any present activity. Therefore, the information stored on the surface today gradually sinks to lower level as time goes, making brain cells free for new data processing of day-to-day activity activities. In the same way as a wave on the water surface moves ahead vacating the space for the succeeding wave that follows behind. This is a reason for forgetting old, past information.

-Yugrishi Vedmoorti Pt. Shriram Sharma Acharya
The Scientific Approach to Sharpen Wit and Wisdom: Page 30.